1. Field of the Invention
This invention relates to access control for digital content. Examples of such content include at least one of audio content, video content, metadata content, text content, image content and so on, for example audio visual content.
2. Description of the Prior Art
The growth of new digital infrastructures, including digital devices and high-speed networks, combined with increasing processor power is making content creation, manipulation and distribution both simpler and faster. While this greatly aids legitimate usage of the content, a disadvantage is that unauthorised abuse of such content (particularly copyright content), such as unauthorised reproduction or distribution, is also becoming easier and more damaging to the content owner.
The situation is made more complicated in that commercial considerations may require the content owner to allow a potential customer to see or use the content in a trial situation before committing to purchase rights to use the content from the owner.
So-called digital rights management (DRM) systems have been proposed, in order to try to address these problems. Known DRM systems generally use a form of data encryption to encrypt content for distribution. An authorised recipient is supplied with a decryption key to allow the recipient to decrypt the encrypted content.
This is a rather basic way to provide access control to content; it is cumbersome and lacks flexibility. All of the data used to provide access (including in this case the decryption keys and associated access permissions data) is stored separately from the recorded information content to which it relates. This creates a problem since a database of some kind must be maintained to keep track of content and the related access data. All of these disadvantages combine to reduce workplace productivity.